I do not know where my wife is. How can I file for a divorce?

We are Hindu couple, married in 1993 and have two adult sons. Elder one is pursuing post graduation and younger one is doing Merchant Navy. In Feb 16, I discovered that my wife was cheating on me. I don't know from how many months or years. I do not know who the third person is and I do not hold any physical evidence against her. I noticed some unusual things and confronted my wife. She once partially admitted about her involvement but later backed out. We separated on 12 Apr 16. On 4th Jul 16 she contacted me and wanted to come back. Both children had also left with her. I allowed her to come back on certain promises. Later she did not keep any of her promises and continued with the same stuff. We again had a fight on 16th Sep 16 and separated. Both children are still with her and I am living alone. I do not have any property. We were staying in a rented house. I don't even know where they are. I want to have divorce from my wife. Could you please on the Cons & Pro and the procedure?